Molecular-sieve zeolites, Nafion membranes, low-density polyethylene films, and mixed surfactant vesicles have been used as microreactors to carry out organic photochemical reactions. The photo-cycloadditions of diaryl compounds with long flexible chains included in NaY zeolite or low-density polyethylene films yield intramolecular photocyclomers to the exclusion of intermolecular products. The...

Ab initio electronic structure calculations with RHF, MP2, and CCSD(T) wave functions have been used to investigate a reaction path for the hydrosilation reaction catalyzed by divalent titanium (modeled by TiH2). Optimized structures and energies are presented. All levels of theory predict a barrierless reaction path compared to a barrier of 78 kcal/mol for the uncatalyzed reaction. The use of ...

Predicting accurate bond length alternations (BLAs) in long conjugated oligomers has been a significant challenge for electronic-structure methods for many decades, made particularly important by the close relationships between BLA and the rich optoelectronic properties of π-delocalized systems. Here, we test the accuracy of recently developed, and increasingly popular, double hybrid (DH) funct...

Zeolites with the faujasite structure (FAU) are extensively used as catalysts and in gas separation. A detailed knowledge of their structure, particularly the positions of extra−framework cations in the case of gas adsorption, is therefore central to understanding their performance. Typically zeolites X (Si/Al ~.1.1−1.5) and Y (Si/Al ~5−11) are used. A common assertion of structural determinati...

The chemistry of radicals adsorbed on zeolites is remarkable in that the products of radical-radical reactions, which are nonselective in solution, can be made selective and can be controlled by supramolecular effects and magnetic isotope effects. The photolysis of ketones adsorbed on zeolites can be manipulated so that either primary or secondary radicals produced by photolysis can be directed...

We have investigated various silica zeolites using density functional theory with periodic supercells, plane waves, and pseudopotentials. These zeolitic phases include silica sodalite, chabazite, mordenite, silica LTA, and silicalite. Atom-level geometries, elastic properties, and cohesive energies are presented. Although the zeolites exhibit a wide range of Si-O-Si angles and densities, the co...

guishing high and low Si/Al ratio zeolites and may be important in studies of zeolites that are chemically or physically altered. ence Foundation under Grant CHE 8204417 is gratefully acknowledged. We thank Professor T. L. Barr, Professor J. Vedrine, Dr. C. D. Wagner, Dr. J. M. Stencel, and Dr. T. D. Debies for helpful discussions and for their comments and suggestions concerning this manuscrip...

The development of new technologies has an impact on a better understanding of the components present in inter/circum-stellar space and also of the interactions of different species.[1] That is one of Astrochemistry focus, and it is a challenge for the scientists, even more due to the limited access and knowledge on that characteristic environment. [2,3] Therefore, the study of interactions bet...

We present a reduced scaling and exact reformulation of state specific complete active space second-order perturbation (CASPT2) analytical gradients in terms the MP2 Fock derivatives using supporting subspace method. This work follows naturally from formulation CASPT2 energy dressed orbitals builds. For given configuration, corresponding to MP2-gradient can be evaluated with O(N5) operations, w...

Various metal-β zeolites have been synthesized under similar ion-exchange conditions. During the exchange process, the nature and acid strength of the used cations modified the composition and textural properties as well as the Brönsted and Lewis acidity of the final materials. Zeolites exchanged with divalent cations showed a clear decrease of their surface Brönsted acidity and an increase of ...